1. Field of the Invention
The present invention relates to a driving device and an image forming apparatus.
2. Description of the Related Art
An image forming apparatus provided to a copier, a printer, a facsimile, and a multifunction peripheral including the functions of a copier, a printer, and a facsimile have many driving devices to perform image forming operations. Such driving devices are used in operating a photoconductor, a transfer belt, and the like. In such an image forming apparatus including driving devices, problematic noise is generated in the image forming operations. In image forming apparatuses, many components are mechanically connected to one another, a driving force from the driving device is transmitted to such components, and noise is generated due to vibrations of the components and or the like. To reduce such noise, many inventions have been invented.
Japanese Patent Application Laid-open No. 2009-164668 discloses an invention for preventing vibrations related to a driving device in an image reading unit included in an image forming apparatus. As illustrated in FIG. 12, a motor 200 that is a driving device is fixed to a support plate 201 with motor fixing screws 202. The support plate 201 is fixed to a housing, not illustrated, with three support plate fixing screws 204, with vibration insulating members 203 interposed between the housing and the respective support plate fixing screws 204. A drive output gear, not illustrated, and a driving pulley 206 are provided on the side of the support plate 201 rear with respect to the side on which the motor 200 is mounted. The driving force of the motor 200 is transmitted to the driving pulley 206 via the drive output gear, and the driving pulley 206 transmits the driving force to a belt 207. The support plate 201 also includes an inclination adjustment screw 210 for adjusting the inclination of the support plate 201, such an adjustment made by adjusting how tightly the screw is fastened. In this manner, the support plate 201 is prevented from being inclined with respect to the housing. This prevents increase of the vibration due to worse engagement with the belt 207 caused by the position shift of the driving pulley 206, and/or the like.
Japanese Patent Application Laid-open No. 2007-3964 discloses, because humans tend to feel more uncomfortable with high-frequency sound, an image forming apparatus that makes high-frequency sound less audible by classifying the vibrations generated inside the image forming apparatus into high-frequency sound and low-frequency sound, and increasing the level of the low-frequency sound so that the low-frequency sound is less audible. Japanese Patent Application Laid-open No. 2007-3964 also discloses a technology for reducing the noise itself in the apparatus, by making the motor movement smoother by reducing the step angle of the motor, or by providing a sound absorber to a wall so that the sound generated internal of the wall is absorbed by the sound absorber.
Countermeasures for the noise in the image forming apparatus have been implemented, including those using a vibration absorber and a sound absorber, and making high-frequency sound less audible, as disclosed in Japanese Patent Application Laid-open No. 2009-164668 and Japanese Patent Application Laid-open No. 2007-3964, for example, and have succeeded in removing the noise to some extent. These countermeasures are, however, not always effective because there are many different types of image forming apparatuses, and the image forming apparatuses have many driving devices that use different mechanisms. Furthermore, from the viewpoint of further reducing the noise level, it is more preferable to have many countermeasures for coping with the noise for different types of image forming apparatuses.
In view of the above, there is a need to provide a driving device and an image forming apparatus capable of coping with the noise easily and in a manner different from those explained above.